J. Entomol. Res. Soc., 17(2): 59-71, 2015 ISSN:1302-0250 What Moths Fly in Winter? The Assemblage of Moths Active in a Temperate Deciduous Forest During the Cold Season in Central Poland Jacek HIKISZ1 Agnieszka SOSZYŃSKA-MAJ2* Department of Invertebrate Zoology and Hydrobiology, University of Lodz, Banacha 12/16, 90-237 Łódź, POLAND, e-mails: 1 [email protected], 2*[email protected] ABSTRACT The composition and seasonal dynamics of the moth assemblage active in a temperate deciduous forest of Central Poland in autumn and spring was studied in two seasons 2007/2008 and 2008/2009. The standard light trapping method was used and, in addition, tree trunks were searched for resting moths. 42 species of moths from six families were found using both methods. The family Geometridae was predominant in terms of the numbers of individuals collected. Two geometrid species - Alsophila aescularia and Operophtera brumata - were defined as characteristic of the assemblage investigated. Late autumn and spring were richest in the numbers of species, whereas the species diversity was the lowest in mid-winter. Regression analysis showed that a temperature rise increased the species diversity of Geometridae but that rising air pressure negatively affected the abundance of Noctuidae. Key words: Lepidoptera, Geometridae, Noctuidae, autumn-spring activity, winter, phenology, atmospheric conditions, regression, Central Poland. INTRODUCTION The seasonal weather changes in a temperate climate have a great impact on poikilothermic animals, as they have a limited ability to regulate their body temperature. Thus, the earliest and most easily detectable response to climate change is an adjustment of species phenology (Huntley, 2007). In recent years, global climate change has become an important scientific topic, and its impact on insects is wildly and intensively investigated (e.g. Jepsen et al., 2008; Kiritani, 2013; Nooten et al., 2014; Williams and Hellmann, 2012a, b). Invertebrates active from autumn through early spring are strongly dependent on weather and snow cover (Moerkens et al., 2012, Legault and Weis, 2013; Williams et al., 2014). Thus, this fauna is well suited for observing changes in annual cycles, seasonal changes in composition and the impact of atmospheric factors on activity (Martin-Vega and Baz, 2013; Mikova et al., 2013; Soszyńska-Maj and Jaskuła, 2013; Soszyńska-Maj et al., in press). In a temperate climate most invertebrates are inactive during the cold part of the year, i.e. late autumn, winter and early spring. However, some insects remain active, fly or swarm in winter despite the low temperatures. During hard frosts they look for shelter and enter quiescence. Some of those species are regularly recorded on the snow surface, while a great number of invertebrates remain active for almost the whole 60 HIKISZ, J., SOSZYŃSKA-MAJ, A. winter in the leaf litter and soil using the excellent insulation capacity of the snow to prevent freezing (Aitchison, 2001). Flies (Diptera), snow scorpion flies (Mecoptera), spiders (Araneida), springtails (Collembola), beetles (Coleoptera) and even earwigs (Dermaptera) are well-known for winter phenology. These insects could be either multivoltine (e.g. Chironomidae, Diptera), some spend the warmer part of the year in larval (e.g. Plecoptera) or pupal (Boreidae, Trichoceridae) stages or even long-lived as some Coleoptera (e.g. Itämies and Lindgren, 1989; Aitchison, 2001; Soszyńska, 2004; Hågvar, 2010; Hågvar and Hågvar 2011; Jaskuła and Soszyńska-Maj, 2011; Soszyńska-Maj and Jaskuła, 2013; Soszyńska-Maj et al., in press). Some moths are adapted to remain active during winter even when the temperature falls below 0oC; they belong to the small number of Lepidoptera that overwinter as an imago (about 100 species in Poland). This strategy is supported by morphological (brachypterous or apterous forms), physiological (accumulation of antifreeze agents) and behavioural adaptations (with standing cold periods in suitable places with a higher temperature, supplementary feeding, dispersion) (e.g. Buszko and Nowacki, 1990, 1991; Sattler, 1991; Leather et al., 1993; Soszyńska-Maj and Buszko, 2011). The main aims of this study were to describe the composition and seasonal dynamics of the moth assemblage active during the cold period in a deciduous forest in Central Poland and to assess the influence of atmospheric factors on their activity. MATERIAL AND METHODS The study area is located in Central Poland in the Las Łagiewnicki forest complex (51o50’30’’N, 19o28’13’’E, UTM CC94), which lies within the administrative borders of the city of Łódź. It covers an area of ​​1200 hectares and is one of the largest urban forests in Europe. With its higher elevation (highest peak 260 m above sea level) the average air temperatures are lower, the humidity higher and the duration of snow cover longer than in the areas of surrounding lowlands. The dominant tree species in the Łagiewniki Forest are oaks (Quercus spp.), which make up 42% of the entire tree stand. The study site was located on the edge of a dry-ground forest (Tilio-Carpinetum typicum) with a proportion of riverside carr Fraxino-Alnetum and near a small pond (Molinio-Arrhenatheretea) (Kurowski, 1998). The investigation was carried out from October to April in two consecutive autumn-spring seasons 2007/08 and 2008/09. The autumn-spring active moths were light-trapped using a 250W mercury-vapour lamp. Trapping started at dusk and lasted until the end of the moths’ activity; this was done at intervals of 7-10 days. Light trapping was not done when the temperature dropped below -10°C. During the research, temperature and humidity were recorded daily; the corresponding data from the local weather station were also noted. During the first season, resting moths were also taken from tree trunks. All the moths collected were killed with ethyl acetate. The moths were identified to species level. The material is deposited in the collection of the Department of Invertebrate Zoology and Hydrobiology, University of Łódź, Poland. In order to analyse the biocoenotic structure of the moth assemblage, dominance (D), frequency (F) and ecological significance (Q) were calculated. Index classes 61 What Moths Fly in Winter? The Assemblage of Moths Active were used according to Kasprzak and Niedbała (1981) and modified to account for the specificity of the assemblage: D5. eudominants: ≥10.1%, D4. dominants: 5.1-10%, D3- subdominants: 2.1-5.0%, D2. recedents: 1.1-2.0%, D1. subrecedents: ≤1.0%; Frequency: F5. very common: 40.1-100%, F4. frequent: 20.1-40%, F3. frequent average: 10.1-20%, F2. rare: 5.1-10%, F1. very rare: ≤5.0%. The ecological significance (Q index) is the geometric mean of frequency and dominance: Q4. taxa characteristic, exclusive and selective: >15.1%, Q3. associated taxa: 7.1-15%, Q2. less associated taxa: 3.1-7%, Q1. random taxa: <3.0%. To find out whether there is any relationship between weather conditions and the number of moths flying, Pearson’s correlation coefficients were calculated at the significance level p<0.05. Variables including the number of individuals and the number of species caught by light trapping in two seasons in a particular ten-day period of a month and the average value of each of the weather parameters at that time were taken into account for the calculation. The null hypothesis of no correlation between weather conditions and moth activity was tested. Regression analysis was carried out to find out if weather conditions had any impact on the winter activity of moths. All the statistical calculations were done in Statistica 10.0 (StatSoft, 2011). RESULTS 42 species of moths from six families were found as a result of autumn-spring investigations. Light trapping in two autumn-spring seasons 2007/08 and 2008/09 yielded 442 specimens of moths from five families and 34 species. During that time no apterous females were found. Fig. 1 shows the percentages of moth families in the material. Two species belonging to the family Geometridae, Alsophila aescularia (Denis and Schiffermüller) and Operophtera brumata (Linnaeus), clearly predominated in the material from light trapping. Based on the Q index, the species characteristic of the autumn-spring moths assemblage were A. aescularia and O. brumata. Most of the species could be regarded as rare and very rare. Table 1 lists all the species collected by light-trapping and their biocoenotic indices. Tree trunk searches yielded 40 moths from three families and 15 species. Table 2 lists these species including sampling dates. a b Drepanidae Drepanidae Lasiocampidae Lasiocampidae Noctuidae Depressariidae 0,1% 3% 1% 3% 1% DepressariidaeNoctuidae 9% Geometridae Geometridae Depressariidae Noctuidae Depressariidae 28% Noctuidae Drepanidae 47% Drepanidae Geometridae Lasiocampidae Geometridae Lasiocampidae 70% 38% Fig. 1. Percentage of moth families collected in a temperate deciduous forest of Central Poland in two win- ter seasons 2007/2008 and 2008/2009: a. with respect to the number of specimens, b. with respect to the number of species. 62 HIKISZ, J., SOSZYŃSKA-MAJ, A. Table 1. Moths collected using a light trap in two winters 2007/2008 and 2008/2009 in Central Poland in systematic order with classes of biocoenotic factors: No. number of specimens collected, D. dominance, F. frequency, Q. ecological significance. No. of Family Species D F Q specimens Agonopterix ocellana (Fabricius, 1775) 1 D1 F1 Q1 Depressariidae Semioscopis avellanella (Hübner, 1793) 1 D1 F1 Q1 Semioscopis steinkellneriana (Denis and Schiffermüller, 1775) 1 D1 F1 Q1 Drepanidae Achlya flavicornis (Linnaeus, 1758) 2 D1 F1 Q1 Agriopis leucophaearia (Denis and Schiffermüller, 1775) 6 D2 F2 Q2 Agriopis marginaria (Fabricius, 1776) 10 D3 F3 Q2 Alsophila aceraria (Denis and Schiffermüller, 1775) 14 D3 F2 Q2 Alsophila aescularia (Denis and Schiffermüller, 1775) 141 D5 F3 Q4 Apocheima hispidaria (Denis and Schiffermüller, 1775) 3 D1 F2 Q1 Biston strataria (Hufnagel, 1767) 1 D1 F1 Q1 Chloroclysta siterata (Hufnagel, 1767) 1 D1 F1 Q1 Geometridae Ectropis crepuscularia (Denis and Schiffermüller, 1775) 2 D1 F2 Q1 Epirrita sp.